Flasher relays



F. STEWART FLASHER RELAYS May 2, 1961 2 Sheets-Sheet 1 Filed Oct. 14, 1957 INVENTOR.

Frederic Szfewan HIS AT TORNE' Y y 2, 1961 F. STEWART 2,982,871

FLASHER RELAYS Filed Oct. 14, 1957 2 Sheets-Sheet 2 fi A- 61 52 a5- 54 5 Q A A A A| .55

INVENTOR. Hedez'ic SLewaI- BY 41/. A ,W.

- HIS ATTORNEY FLASHER RELAYS Frederic Stewart, Brighton, Victoria, Australia, assignor to McKenzie & Holland toria, Australia (Australia) Pty. Ltd., We-

The present invention relates to polarized relays and particularly to relays of the oscillating armature type commonly known as flasher relays for controlling intermittently illuminated light sources of visual signal indicators used as warning devices at railway, roadway and tramway intersections.

It is a principal object of the present invention to provide in polarized relays, an improvement in the form of simpleand effective means to control the rate of oscillations or frequency of a pivoted armature to uniformly open and close a circuit at relatively low speed suitable, for example, for controlling a light source for visual or warning signal devices of the flashing type.

The periodic or intermittent opening and closing of the circuit may be such as to provide between 20 to 60 flashes per minute, a desired rate being about 40 flashes per minute of a light source which is at present a standard rate for American railroads.

It is another object of the present invention to provide a speed controlled relay which may be employed as a circuit breaker for general purposes. Contacts driven or actuated by the relay armature can open and close any circuit through said contacts for the control of another circuit or device as may be required.

It is a further object of the present invention to provide a magnetic calibrating shunt bridging a pair of electromagnetic pole pieces of an oscillating armature type relay.

It is yet another object of the present invention to provide a polarized relay of the oscillating armature type having a coil mounted upon a core, and an element composed of high conductive material for controlling the magnetic flux developed in said coil to a. degree necessary to operate a pivoted armature at a relatively low speed for operating the contacts of a signal indicator. 7

In the attainment of the foregoing objects of the present invention I provide a relay of the oscillating armature type comprising a pair of electromagnetically energized pole pieces and at least one associated core and coil, 2 pair of permanently magnetized pole pieces mounted in spaced relation to said electromagnetic pole pieces and forming an air gap therebetween, and an armature pivotally mounted for oscillatory movement in said air gap. A shunt member may be connected to bridge said electromagnetically energized pole pieces, and a copper slug may be afiixed to said core to decrease the change of flux of said core member.

Other objects and advantages of my invention will become apparent from the following description and the accompanying drawings in which:

Fig. l is a view partly in cross section of a polarized relay according to the present invention,

Fig. 2a is a schematic view of a magnetic structure for a relay of the type shown in Fig. l and including a shunting bar;

Fig. 2b is a fragmentary bottom view of Fig. 2a;

Fig. 3 is a partial schematic view showing another core and coil arrangement for a relay .of "the type shown in Fig. l;

i atentecl May 2, 1951 Fig. 4 is a partial schematic view of another coil arrangement for a relay of the type shown in Fig. 1; and

Fig. 5 is a schematic view of another arrangement, the core and coil elements for a relay of the type shown in Fig. 1.

I shall first describe the above embodiments of a polarizcd relay according to the present invention and shall then point out the novel features thereof in the appended claims.

Similar reference characters refer to similar parts in each of the several views.

Referring first to Fig. 1, there is shown a relay 10 according to the present invention which may be of the plug-in type and comprising an electromagnet including two pole pieces 11 and 13 secured as by riveting to a nonmagnetizable supporting bracket 15, which supporting bracket in turn is fastened by screws, not shown, to a back plate 17 of suitable insulating material. Mounted to the back plate 17 and enclosing the elements of the relay is a glass or plastic cover 19. A latch 21 is provided for for mounting the relay in position. The pole pieces 11 and 13 extend upwardly through slots, not shown, formed in the bracket 15, and are provided at the upper ends with outwardly extending portions 11a and 13a. The electromagnet includes a magnetizable core piece 23 which is secured to and spans the outwardly extending portions 11a and 13a, and is atlixed thereto by means of screws 25. An insulating coil winding 27 is mounted on core piece 23. Coil 27 is provided with an insulating cover 29.

A portion of pole pieces 11 and 13 extend toward each other and have their lower pole faces 11b and 13b positioned to lie in the same horizontal plane. A pair of L-shaped permanent magnets 33 and 35 are provided. One end of permanent magnet 33 is secured to the pole piece 11 and the other end thereof extends parallel to and underneath the pole face 11b. An air gap is formed between the permanent magnet 33 and pole face 1112. Permanent magnet 35 is similarly aflixed to pole piece 13 and an air gap is also formed between permanent magnet 35 and pole face 13b. The ends of the permanent magnets 33 and 35 extending parallel to pole faces 11b and 13b have the same polarity.

A magnetizable armature 31 is pivotally supported at its center by trunnion screws 20 extending through support -16 which is in turn attached to bracket 15 by screw 18. The armature 31 is arranged for swinging movement in the air gap between the permanent magnets 33 and 35 and pole pieces 11 and 13. As one end of the armature 31 isswung away from pole piece 11 it will be swung toward permanent magnet 33; concurrently the other end of the armature will be swung toward pole piece 13 and toward permanent magnet 35, and vice versa. The armature 31 is prevented from actually touching the pole pieces 11 and 13 by means of core pins 22 of nonmagnetizable material secured to the armature, adjacent its ends, in a position to engage the pole pieces 11 and 13 before the armature comes into contact therewith. The permanent magnets 33 and 35 are positioned with relation to the-pole pieces 11 and 13 such that when pins 22 engage their respective pole piece, a small air gap is maintained between the opposite end of the armature 3-1 and the associated permanent magnet.

A contact actuating member 37 is journalled to a bracket 36 aflixed to one end of the armature 31 and is arranged to be actuated vertically by the armature. Movable contacts 49 and 50 attach onto posts 39 and 41 on member 37. in the lowermost position of the left- 'hand end of armature 31, as shown in Fig. l, and consequently, the lowermost position of contact actuating member 37, movable contacts 49 and 50 are caused to engage stationary contacts 52 and 54, respectively. In the reverse position of armature 31 and consequently the uppermost position of contact actuating member 37, movable contacts 49 and 50 are caused to engage stationary contacts 1 and 53, respectively.

' The'arrangement of the permanent magnets 33 and 35 provides-a means of maintaining the armature 31 in one position or the other when current is removed from the relay. If the removal of current occurs when the armature 31 is in a horizontal position, the weight of the contact actuating member 37 and the movable contact fingers 49 and Sit afiixed to one end of the armature act as a bias to ensure that the armature will not float, but will assume one or the other of its operating positions, so ensuring that some of the contacts connecting to the coils are always closed when the relay is deenergized.

In Fig. 2a, the magnetic circuitry of the relay of Fig. l is shown. schematically in order to facilitate the description thereof. The terminal 3% of the coil 27 connects to stationary contacts 52 and 53 while the terminal 32 of coil 27 connects to stationary contacts 51 and 54, all of which are also shown schematically. In the position of the armature 51 as shown in Figs. 1 and 2a, that is, with opposite ends thereof adjacent pole piece 13 and permanent magnet 33, movable contact fingers 49 and 50 engage stationary contacts 52 and 54, respectively. When switch 56 is closed, connections are made to cause a current from the positive terminal of a source 55 to flow through movable contact 50, stationary contact 54, winding 27, stationary contact 52, movable contact 49 and to the negative terminal of source 55. A south polarity is thus induced at the right hand end of the core piece 23 and in pole piece 13. A north polarity will be induced at the right hand end of the armature 31, and a south polarity at the left hand end thereof. The south polarity of permanent magnet 33 will then repel the armature 31. The left hand end of armature 31 will thus swing upwards and the right hand end will swing downward, pivoting on screws 20.

As the left hand end of armature 31 swings toward pole piece 11 the movable contacts 49 and 51 are caused to engage stationary contacts 51 and 53, respectively. Current from source 55 will flow through the coil 27 in a direction opposite'to that noted above and the flux produced thereby develops a south polarity at pole piece 11. A north polarity will be induced at the left hand end of the armature 31, and a south polarity at the right hand end thereof. The south polarity of permanent magnet 35 will tend to repel the armature 31. The right hand end of armature 31 will thus swing upwards and the left hand end will swing downward pivoting on screws 29.

As the right hand end of armature 31 swings toward pole piece 13 the movable contacts 49 and 51 are caused to engage stationary contacts 52 and 54, respectively, to repeat the cycle causing sustained oscillations of the armature.

It will be appreciated that the relay alternately energize itself for pole changing over its own contacts.

The oscillation of the armature 31 is performed at a controlled speed, contacts not shown but similar to contacts 49-54 and driven by the armature may open and close any circuit to operate, for example, a light and cause that light to flash at the rate at which the armature oscillates.

' In some instances it may be advantageous to provide a pair of flanged channel shaped shunt members 43 and 45, see Figs. 2a and 2b, which bridge and arealfixed to pole pieces 11' and .13, as by screws 44. Members 43 '45 provide a magnetic calibrating shunt for achieving a steady and controlled rate of oscillation at the relatively V contact 51, while a second coil terminal 72 conn'ects to stationary contact 52. When switch 56 is closed the center tap terminal 71 connects in series through source 55 to movable contact 49. A similar operation to that noted above will occur and current will flow through the coil winding 67 through each half of the winding in opposite directions, in sequence, to cause the armature to oscillate.

. Fig. 4 shows another embodiment of the relay 10, one in which two coils 73 and 74 are employed; It has been found desirable for some applications to use a pair of coils providing a high level of magnetic energize.- tion and to shunt the excess fiux by the calibrating magnetic shunt members 43 and 45 shown in Figs. 2a and 2b. Terminals 75 and 76 of coil 73 are connected to stationary contacts 51 and 53, respectively, and terminals 77 and 78 of coil 74 are connected to stationary contacts 52 and 54, respectively. When switch 56 is closed,

a source 55 is connected in series with a resistor 64 be tween movable contacts 49 and 50. The coils 73 and 74 will be fed alternately with current in opposite direction to produce a continuing oscillation. By using coils of comparatively low resistance in association with a series resistor, the said series resistor acts as a ballast and helps to maintain a more uniform operating rate during any variation of the supply voltage.

Fig. 5 shows another embodiment of the relay 10, one in which a pair of coils 79 and 80 are connected in series. Terminal 81 of coil 79 is connected to terminal 83 of coil 80 and both terminals are connected to movable contact 49. Terminal 82 of coil 79 is connected to stationary contact 52 and through a switch 56, shown in its closed position to one terminal of source 55. Terminal 84 of coil 80 is connected to stationary contact 51 and to the other terminal of source 55. In this embodiment, as the armature oscillates the movable contact 49 will alternately engage stationary contacts 51 and 52 to alternately energize coil 80 by current flowing in one direction and to short out coil 79, and then energize coil 79 by current flowing in an opposite direction and to short out coil 80.

The core 85 on which the coils 79 and 86 are wound has a copper slug 86 mounted in the center portion between the two coils. The slug 86 functions to retard the build-up and die-down of the magnetic flux produced by the current in the coil and so contributes to the desired slow rate of operation of the relay.

While my invention has been described with reference to a particular embodiment thereof, it will be understood that various changes and modifications may be made by those skilled in the art without departing from the invention. The appended claims are therefore intended to cover all such modifications within the true spirit and scope of the invention. v

Having'thus described my invention, what I claim is:

V 1. A relay of the oscillating armature type comprising a pair of electromagnetically energized pole pieces; a pair of permanently magnetized pole pieces mounted in spaced relation to said electromagnetic pole pieces and forming an air gap therebetween, an armature pivotally mounted for oscillatory movement in said air gap, said pivoted armature being movable between two extreme positions with one end thereof being moved toward an electromagnetically energized pole piece as the opposite end thereof is moved toward a permanently magnetized pole piece, and a shunting member connecting saidelectromagnetically energized pole pieces.

2. A relay of the oscillating'armature type comprising a pair of spaced apart electromag'ntically energizedpole pieces, a pair of permanently magnetized pole pieces mounted in spaced relation to said electromagnetic pole pieces and f orming an air gap therebetween, an armature' pivotally mounted for oscillatory'movement in said air gap, said armature operating to causesaid. electro- .magn tically energized pole pieces to be alternately enerand at leastzone gized by energy of opposite-polarity,

References Cited in the file of this patent UNITED STATES PATENTS Finnigan Jan. 25, 1916 Ballantine July 4, 1939 6 FOREIGN PATENTS Great Britain Jan. 17, 1940 Great Britain Feb. 2, 1944 France Oct. 29, 1941 

